The invention relates to carbon dioxide recovery from fossil fuel based power generation plants using aqueous solutions of amine-based solvents such as mono-ethanol amine (MEA), methyldiethanolamine (MDEA), OASE®-blue from BASF and KS-1 solvents from MHI.
To recover carbon dioxide, it is first absorbed from a gas mixture by contacting the gas with a water solution of amine-based solvent inside an absorber, followed by desorbing the carbon dioxide in a regenerator or stripper and recirculating the regenerated solvent back to the absorber. It is known that the absorption process is enhanced by increased pressure and reduced temperature while the regeneration process is favored by reduced pressure and increased solvent temperature. Increased temperature required for the regeneration within the stripper requires significant amount of thermal energy which is typically proved by a condensation of low pressure saturated steam to heat up a reboiler used for boiling a mixture of carbon dioxide and solvent at the bottom of the stripper.
Significant efforts have been made in discovering new solvents which would require less energy for carbon dioxide absorption and would exhibit higher resistance to oxidative and thermal degradation while allowing for more favorable operating conditions resulting in more energy efficient carbon dioxide recovery processes. In order to enhance carbon dioxide absorption, process improvements such as using an absorber intercooler to control the temperature rise of the solvent due to the exothermicity of the carbon dioxide absorption process have been proposed and implemented in commercial plants.
Additionally, few recent post combustion capture process configurations such as positioning a flue gas blower downstream from the absorber are aimed to reduce post combustion capture parasitic load and to consequently increase net power generation efficiency.